Strawberry FaNAC2 Enhances Tolerance to Abiotic Stress by Regulating Proline Metabolism

Abstract

The quality and yields of strawberry plants are seriously affected by abiotic stress every year. NAC (NAM, ATAF, CUC) transcription factors are plant-specific, having various functions in plant development and response to stress. In our study, FaNAC2 from strawberry (Fragaria × ananassa, cultivar “Benihoppe”) was isolated and found to be a member of the ATAF sub-family, belonging to the NAC family of transcription factors. FaNAC2 was strongly expressed in the shoot apical meristem and older leaves of strawberries, and was induced by cold, high salinity, and drought stress. To investigate how FaNAC2 functions in plant responses to abiotic stress, transgenic Nicotiana benthamiana plants ectopically overexpressing FaNAC2 were generated. The transgenic plants grew better under salt and cold stress, and, during simulated drought treatment, these transgenic lines not only grew better, but also showed higher seed germination rates than wild-type plants. Gene expression analysis revealed that key genes in proline biosynthesis pathways were up-regulated in FaNAC2 overexpression lines, while its catabolic pathway genes were down-regulated and proline was accumulated more with the overexpression of FaNAC2 after stress treatments. Furthermore, the gene expression of abscisic acid biosynthesis was also promoted. Our results demonstrate that FaNAC2 plays an important positive role in response to different abiotic stresses and may be further utilized to improve the stress tolerance of strawberry plants.

The GATA factor HANABA TARANU promotes runner formation by regulating axillary bud initiation and outgrowth in cultivated strawberry

“…Previous studies have reported that multiple NAC members are involved in the formation of organ boundaries and meristems, such as NAM in Petunia (Souer et al., 1996), CUC1‐3 in Arabidopsis (Aida et al., 1997; Raman et al., 2008; Vroemen et al., 2003) and CUP in Antirrhinum majus (Weir et al., 2004). Studies on FaNAC2 homologs in other species and in strawberry have focused on its role in resistance to biotic and abiotic stresses, such as ATAF1 in Arabidopsis, OsNAC6 in rice and FaNAC2 in strawberry (Liang et al., 2020; Nakashima et al., 2007; Wu et al., 2009). In this study, we found for the first time that FaNAC2 was involved in runner formation and could directly activate FaHAN by binding to its promoter (Figures 6a and 7f).…”

Genome-wide identification and expression analysis of the NAC transcription factor family in Saccharum spontaneum under different stresses

“… 53 In plants, studies on NAC gene regulation in response to drought, salinity, low-temperature, high-temperature, heavy metals, disease, and other stresses have been published. 54–59 However, few reports about SsNAC genes involved in responses to biotic and abiotic stresses are available. Therefore, this study further analyzed the expression patterns and potential functions of 12 SsNAC genes in response to various biotic and abiotic stresses.…”

Heterologous expression of the cysteine proteinase gene VaCP17 from the cold-adapted grapevine Vitis amurensis increases cold tolerance in Arabidopsis

“…For example, transgenic rice overexpressing ONAC022 are more tolerant to drought and salt stress (Hong et al 2016). The strawberry FaNAC2 gene could be signi cantly induced by cold, salt and drought stresses, and transgenic tobacco expressing FaNAC2 showed increased resistance to cold and salt stresses (Liang et al 2020). Di19 proteins are a subset of the Cys2/His2 zinc nger protein family, which plays an important role in regulating multiple stress responses (Milla et al 2006;Qin et al 2014).…”